This invention relates to computer controlled machine tools and industrial robots in general and more particularly to a method for reducing track errors in computer controlled machine tools or industrial robots, in which distance reference values for the drive control circuits supplied by the computer in a reference value channel determine the track and the track velocity.
It is already known in numerically controlled machine tools to monitor the so-called drag error, i.e., the difference between reference and actual position and, if the drag distance becomes excessive, to initiate countermeasures (see, for instance, DE-AS No. 27 29 372). In this connection, monitoring in such a manner that the ratio of the partial actual values supplied by a distance measuring system and the corresponding speed reference value is formed is also known. These methods have found acceptance; in principle, however, they can become active only if the unpermissible deviation has already occurred. It would be substantially more advantageous if deviations between the desired and the actual track would not occur, as far as possible, from the start.
Accordingly, it is the object of the present invention to describe a method with which the deviation of the reference from the actual track, i.e., the contour error, can be prevented as far as possible, from the start.